The present invention relates to a novel crystalline aluminosilicate zeolite designated NU-85, a method of making it and to processes using it as a catalyst.
As the actual structure of crystalline zeolites is often unknown, these materials are usually characterised by their X-ray powder diffraction pattern, molar composition and sorptive and catalytic properties. Techniques such as electron diffraction, transmission electron microscopy and magic-angle spinning nuclear magnetic resonance spectroscopy can, however, be used to give additional information on certain structural features which would not, otherwise, be observed.
Even when the basic framework structure is known, additional information may be required to distinguish between two materials. For example, zeolites X and Y have the same basic topology but differ in the ratio of silica to alumina in the structural framework. Another example is large- and small-port mordenite. These materials have the same X-ray powder diffraction pattern yet have different molecular sieve properties with the large port material's sorption being consistent with the known framework topology. The reason for these differences has been attributed to the fact that the small port material contains structural blockages within its channels, which, it has been reported, can be observed by electron diffraction.
Materials which are intergrowths of two zeolites having different topologies also exist. Such materials are not simple mixtures. They are materials in which bands of both zeolites exist within individual crystals. Such intergrowths are new materials since they have properties which can distinguish them from the individual "parent" zeolites. Intergrowths based on erionite/offretite and ZSM-5/ZSM-11 have been described in U.S. Pat. Nos. 4,086,186 and 4,229,424 respectively.
Intergrowths may be characterised by electron diffraction and/or transmission electron microscopy. However, it is possible that the intergrowths may have distinct X-ray powder diffraction patterns which differ from the parent zeolites. For example, U.S. Pat. No. 4,086,186 describes a novel aluminosilicate material, designated ZSM-34, which is an intergrowth of erionite-offretite and which has an X-ray powder diffraction pattern which is different from that of either erionite or offretite. Another example is zeolite T which is the subject of U.S. Pat. No. 2,950,952. This is described in "Zeolite Molecular Sieves", D W Breck, published by J Wiley & Sons, 1974, p81 as a "disordered intergrowth" of offretite and erionite". Like zeolite ZSM-34, the X-ray powder diffraction of this material is different from that of the parent zeolites.